Lithium-ion batteries that utilize polyethylene (PE) separators still require improvement. To improve the electrochemical properties and thermal stability of the PE separators, an-ultrathin AlO layer (∼10 nm) was precisely coated onto the surface of a 7 μm thick PE separator via atomic layer deposition. The resulting ultrathin AlO ALD-PE separators exhibited the excellent thermal dimensional stability and flexibility, and the tensile strength was considerably improved. Moreover, the ultrathin AlO ALD-PE separator demonstrated better electrolyte wettability, higher ionic conductivity, and lower interface impedance. The 4.5 V high-voltage LiCoO/Li coin-cells with the PE-75 separator exhibited better initial specific discharge capacity (184.3 mAh/g) and capacity retention rate (96 % after 300 cycles at 0.5C) compared to the PE separator (176.8 mAh/g; 87.7 % after 300 cycles at 0.5C). Furthermore, the Li/PE-75/Li symmetric cell had stably cycled for 1000 h without significant dendrites generation. Finally, the pouch-cell using the PE-75 separator was less prone to thermal runaway at high temperatures, indicating its improved safety.

中文翻译：

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高性能、安全的锂离子电池，采用精密超薄Al2O3涂层聚乙烯隔膜

使用聚乙烯（PE）隔膜的锂离子电池仍需要改进。为了提高PE隔膜的电化学性能和热稳定性，通过原子层沉积将超薄Al2O3层（~10 nm）精确涂覆到7μm厚的PE隔膜的表面上。所得超薄Al2O3 ALD-PE隔膜表现出优异的热尺寸稳定性和柔韧性，并且拉伸强度显着提高。此外，超薄Al2O3 ALD-PE隔膜表现出更好的电解质润湿性、更高的离子电导率和更低的界面阻抗。与 PE 隔膜相比，采用 PE-75 隔膜的 4.5 V 高压 LiCoO/Li 纽扣电池表现出更好的初始比放电容量（184.3 mAh/g）和容量保持率（0.5C 循环 300 次后为 96%）（ 176.8 mAh/g；0.5C 循环 300 次后为 87.7%）。此外，Li/PE-75/Li对称电池稳定循环1000小时，没有明显的枝晶生成。最后，使用 PE-75 隔膜的软包电池在高温下不易发生热失控，这表明其安全性得到了提高。